Remote Plasma Nitrided Oxides (RPNO) (or RPN oxynitrides) have recently shown great promise as a gate dielectric layer in deep submicron CMOS. Its advantages include lower gate leakage by virtue of a thicker dielectric film to achieve the same electrical oxide thickness, a lack of mobility degradation commonly associated with other oxynitrides, excellent boron penetration resistance, and improved PMOS drive current. RPNO films have been demonstrated to have reliability superior to that of a pure silicon oxide film when the overall film thickness is less than about 23 angstroms. Thicker RPNO films have reliability only comparable to that of silicon oxide. This is believed to be due to the non-uniform nitrogen profile obtained in RPNO films. A method to form RPNO films is described in TI-23502.1, application Ser. No. 09/291,844, “Semiconductor device having interfacial nitrogen layers and method of formation”, and is hereby incorporated by reference. The curve shown in FIG. 1 represents a typical nitrogen profile that would be obtained from a RPNO film using a measurement technique such as SIMS or Auger analysis. Region 100 represents the RPNO film and region 110 the silicon substrate on which the RPNO film is formed. The nitrogen concentration 115 is seen to peak at the surface of the RPNO film 100 and decrease towards the silicon substrate 110. Current MOSFET technology requires that the reliability of the gate dielectric layer exceed that of pure silicon oxide. There is therefore a need for a transistor gate dielectric layer with reliability exceeding that of pure silicon oxide.